Listen, I really think the custom terrain you've made looks incredible and is different from normal which makes it look really cool and fun to explore, but it kind of ruins UHC, especially normal mode. The main problem is the tree sizes, they're really big so it means you can't break trees down like you usually would and get apples falling from them, its incredible hard to find any apples at all and takes way too long. Another problem is there don't seem to be any biomes with sugarcane naturally spawning, so it kind of gets rid of efficient enchanting and anvilling for better fights. Also, I don't know if in normal mode the custom terrain has affected the ore generation in any way, but in the few games I have played in normal mode, it seems incredibly hard to find any ores, even things like coal ore is hard to find and I seem to find a lot of emerald ore (even though I'm not in an extreme hills biome) but this could just be in my head. Apart from that I really like the UHC, 1.9 UHC is very, very challenging.